1. Technical Field
The present invention relates to Group III nitride semiconductor crystals used in semiconductor devices and methods for manufacturing the same, Group III nitride semiconductor devices and methods for manufacturing the same, and light-emitting appliances that include those Group III nitride semiconductor devices.
2. Description of the Related Art
Group III nitride semiconductor crystals are widely used in semiconductor devices such as light-emitting diodes (hereinafter called LEDs) and laser diodes (hereafter called LDs).
Conventionally, the manufacture of Group III nitride semiconductor devices that include a Group III nitride semiconductor crystal has required numerous process steps. There was a process of forming a thick Group III nitride semiconductor crystal on a starting substrate, a process of removing this crystal from the starting substrate, a processing of slicing that crystal, a process of attaching the crystal obtained by slicing to the crystal holder of a grinding machine and/or a polishing machine, a process of machining the surface (by this meaning to grind and/or polish; the same hereinafter) of one principal face of the crystal while using increasingly smaller grain-size abrasive, a process of removing the crystal whose one principal face has been machined from the crystal holder, a process of attaching the crystal whose one principal face has been machined to the crystal holder such that its other principal face may be machined, a process of machining the surface of the other principal face of the crystal while using increasingly small diameter abrasive grain, a process of removing the crystal whose two principal faces have been machined from the crystal holder, and a process of cleaning the crystal whose two principal faces have been machined, and by performing these process steps, a highly-clean Group III nitride semiconductor crystal substrate having a predetermined thickness was obtained. One or more Group III nitride semiconductor crystal layers are then formed on this Group III nitride semiconductor crystal substrate and the product is cut into chips of a predetermined size to produce semiconductor devices having a predetermined size (see Patent Document 1, for example).
If the starting substrate is made of a material that is different from the Group III nitride that is to be grown thereon, then to obtain a large Group III nitride semiconductor crystal, further process steps are required. These are a process of growing a 100 μm to 200 μm thick Group III nitride semiconductor crystal atop this dissimilar substrate, a process of removing a portion of the dissimilar substrate, a process of once again growing a 100 μm to 200 μm thick Group III nitride semiconductor crystal, a process of removing the remaining dissimilar substrate, and a process of growing a Group III nitride semiconductor crystal thereon (see Patent Document 2, for example).
Thus, as illustrated above, conventional manufacturing methods have included many processing steps and are inefficient due to the particularly time intensive nature of the processes for slicing, grinding/polishing, and cutting into chips, the Group III nitride semiconductor crystal.
Accordingly, there has been a need for more efficient manufacture of Group III nitride semiconductor devices having a predetermined size.
Patent Document 1: Japanese Unexamined Pat. App. Pub. No. 2002-261014.
Patent Document 2: Japanese Unexamined Pat. App. Pub. No. H11-1399.